High-frequency tube structure



mg. 30, 1949. wpw. HANSEN 2,480,133

HIGH-FREQUENCY TUBE STRUCTURE Original Filed Dec. 22, 1941 PH ASE- AND AMPLITUDE ADJU STEJZ INVENTOR W/z z /AM WHANSEN Patented Aug. 30, 1949 HIGH-FREQUENCY TUBE STRUCTURE William W. Hansen, Garden City, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Original application December 22, 1941, Serial No. 423,930. Divided and this application February 17, 1945, Serial No. 578,394

13 Claims.

This invention relates, generally, to ultra-highfrequency apparatus operable at wavelengths of the order of one hundred to one centimeter, corresponding to frequencies from 300 to 30,000 megacycles per second, and is more particularly concerned with modifications and improvements of electron discharge devices of the type disclosed in Patent No, 2,242,275, issued May 20, 1941, in the name of Russell H. Varian, the purpose of these modifications and improvements being to increase the overall efiiciency of such devices.

The present application is a division of application Serial No. 423,930 for High frequency tube structure, filed December 22, 1941, now Patent No. 2,445,811, issued July 27, 1948.

The device of the above-mentioned Varian patent is therein shown to consist of means providing an electron beam arranged to traverse alternating electric fields of hollow resonant means, thereby causing velocity changes of the electrons and subsequent bunching thereof, the bunches acting to maintain an oscillating ultra high frequency field in the resonant means.

The principal object of the present invention is to provide a novel ultra high frequency tube structure of enhanced efiiciency, obtained by effecting more complete bunohing of the electrons of the electron stream, and by improving the wave form of the buncher apparatus.

A further object is to provide an electron beam velocity modulating device from which outputs of a plurality of different frequencies may be obtained.

Another object of the invention is the provision of resonant cavity means operating at fundamental and harmonic frequencies for producing more complete grouping of the electrons of the stream to thus efiect more complete and efficient conversion of direct current energy to high frequency alternating current energy.

Still another object of the present invention is to provide improved apparatus for producing velocity-grouping of electrons of an electron beam, by providing non-sinusoidal velocity modulation thereof.

Yet a further object is to provide improved velocity modulation electron discharge apparatus having an electron stream modulated non-sinusoidally, such as produced by simultaneous velocity modulation at a fundamental frequency and a harmonic thereof.

Other objects and advantages will become apparent from the specification, taken in connection with the accompanying drawings wherein the invention is embodied in concrete form.

In the drawings,

Fig. 1 is a partial cross-section elevation view of one form of the invention.

Fig. 2 is a partial elevation cross-section view of a modified form of Fig. 1.

Figs. 3 and 4 are explanatory graphs.

Similar characters of reference are used in all of the above figures to indicate corresponding parts.

As disclosed in Varian Patent No. 2,242,275, a conventional velocity modulation electron discharge device comprises an electron gun for producing a uniform velocity electron stream which is projected through an input or buncher cavity resonator which alternately accelerates and decelerates (thus velocity modulating) theelectrons. These velocity-modulated electrons continue in a field-free drift space where the faster electrons overtake the slower ones, resulting in bunching or velocity-grouping of the electrons. This bunched or grouped stream is an electron current having an ultra-high-frequency component (and harmonics thereof) superposed upon a direct current component. This stream passes through 'a second output or catcher resonator and delivers amplified energy of this frequency (or harmonics thereof) to this second resonator. This energy is available for supplying any load, and part of it may be fed back to supply the buncher resonator to sustain the oscillations in the catcher resonator.

The most desirable wave form for the electron beam current entering the energy-extracting resonator of such an electron beam velocity modulation device is a delta function of infinite height and of infinitely narrow width. The term delta function is defined in P. A. M. Diracs Principles of Quantum Mechanics (1937) at page '72 and as used herein means a function having a finite area under its curve while being infinitely narrow. The velocity modulating or buncher resonator, in order to produce a wave form approaching the desired one, must have an electromagnetic field which changes linearly in time, such as shown in Fig. 3. Such a type of velocity modulation produces a desirable sharply pulsed beam at the entrance grid of the second resonator which approaches the desired peaked delta function, shown in Fig. 4, thereby obtaining improved operating efficiencies. The device shown in Fig. 1 operates according to such a principle.

Referring to Fig. 1, there is shown a concave electron emitter surface 14 surrounded by a cooperating focusing ring 15, supported in glass 3 end bell I6. The entire cathode structure is mounted in conducting cylinder H which forms the reentrant portion of a hollow cavity resonator I8 and also supports accelerating grid 19 directly in front of emitter I4. The wall 80 of resonator I 8 carries: the opposite grid 82 and serves as thecomrnc-n'tvall be'tween'resonatorlfi and-a resonator 8I, the resonator BI being tuned to a harmonic of the resonant frequency of resonator I8, preferably the second brthird haTmOnic. A cylindrical tube 84 forms the reentrantportion of resonator BI and supports: grid83""opposite to grid 82. Tube 84 formsthdrift'tube" and constitutes the reentrant portion of a resonator 96 and supports a gridfi s'l: -inwits end a oppositez grid 88 in the common wallil3 between resonator 86 and another resonator 90. Resonator 96 is tuned to the same harmonic frequency asresonator 8 I, while resonator 99 is tuned to the same resonant frequency as" resonator l8. A .tube 9| forms the reentrant portion br-"resonatorto; sup- "porting a grid structure"89 adjacent to gridBB of Wall 93. Tube 9| may e'tenninatedm'reentrant Eohi'ca1end"plece"9 2 which may serve ""tofdirect secondary electrons (emitted when high velocity Focusing coil I '0 may be supplied by' a con- 1 "Electrons from'emitter' surface 14 are"'accel- "18, the "electron" b'eam 'suffers recurrent changes "fin'electronyelocity;"that 'is';'is" velocity modulated; ahd;"in"pass'ingbn through 'dr'ift tube 94'; becomes ffgrouped or. "density modulated. Thesdg'rouped emctron's're ease high frequency energy'on jagain coming to a"f0cus 1near"grid88, "generatingand maintainin ;an pseiliating electromagnetic field ISCSIIat'Of BU. Eli'eTgy maintain Oscillations in resonator I 8'' may "then be' coupled-back from "'jr es'o'riator 99throu'ghconcentric line el'ement's 99, llzfand 95,"cooperating with coupling 'loops' lln ahd l 04,

disclosed in priofI-Iansen andVarian' Pat- "nt *No. 2,281I935', for Modulation system; granted proper" adjustment of element I 07; resonatoft I may be excited so that the combined eifectsbf lithe" oscillating'electridfields inles'ori'atorslil and k "3l'is"t0'-15I" O"dliCE a' resultant'action-bn thebeam *rrcm-eatnouefirwnrcrrapproximates that which" *"May 511942, 'the electron" beam current entering would be produced by the desired saw tooth Wave form of Fig. 3, as is well known in the art of Fourier analysis. The system is thus self-oscillatory, operating with considerably enhanced efficiency, and with output ultra high frequency .--DOWerz removable by means of coupling: 100p I08 "and concentric line element 98.

Additional concentric lines 91 may be coupled -to the harmonic field inside resonator 86, so that thezndevice.'mayi have an output of two differing frequencies, with no necessity for interposing fil- -"termeansion-separating them. The device may alsd-beu'sedasan amplifier, when elements I04, 95, I92, 99 arid'193 are omitted, energy being introducedsto theiamplifier by coaxial line 94 and removedby meansxof line 98.

lt is evident:tonne skilled in the art that resonators. 8| and 86 may be made resonant to any 'desirable harmonic of the frequency at which resonators I8 and 9l operate. It is also evident that, in addition to the'harmonicresonators B I- and B G there may be "supplied {other -andadditional harmonic resonators attached toea'ch-'-f-undamentalresonator-18TH.

*Ihe' device of FigR-2'operates similarlytmth'at 'shownin- Fig; 1. In-this-deviee resonators-86 and spherical segment shape having opposed: reentra'nt cone-shapdpoles, 'such'a device-having 'been previously described"- in-prior ap'plicationS erial' 'No: 416,170; filed October 23;1941, now -Pat- 'ent No. 2,425,738 {issued-August 19,'-'=1-947,-'-in the Sigurd F; Varian, and-Russell -H5'Varian. Asexplained therein, a resonator" such-asdevice H 0 is capableof having-an oscillating electromag- "fundamental frequencyand atan "odd" harmonic frequency. Energy at each of these-frequencies 'may beextracted-independeritly "of *the other 'f-requencyby properly positioned coupling elements,

-"and FI 43-respectiVely; of-resonator I I 9 are spaced approximately omeach side of the focal spot produced in the electron'be'am' by coil "I00. Tube -I I 6 is attached to cone- II 4= opposite -tube-"B4, and has its end opposite aperture -II 2 closedby-reen't-raht conical portion "I I 'I', which serves-to reflect -secondary electrons" (produced whenthe '--'primary "electron beam "strikescone '92) 'towardthe walls of tube II'S rather than back into resonator H0.

"Glass tube H8 is'pr'ovided concentric-to tubes 84 ill and I I 8 toprovide continuity tothe'vacuum'envelo'pe; and is placed 'whereit haSTtheIeaStBfi'GCt "upon the two oscillating electric fields. Tube H 8 may *preferablybefplaced at' a position "of zero tatable by knob. I'ZII'in a position: such as "shown *in'the drawings, its position being that .WhiChdiS- turbs the fundamental electric field and notthe harmonic field. Similarly; paddle ML-rotatable .byknob I22; is'plac'ed'sothat it does notdisturb "the"fundamental ele'ctricfield',but does alter the 'harm'onifield. "Inthis mannerjthe-fu'ndamen- "tal" and harmonidfields may be" -ind'epend'ei'itly tuned.

The device may'be: made to operate'as'an oscil- .lator' bycoupling-loop"I'23to resonatoria through ""concentridlinepostsI"24*and95."Resonatorf18,

being tuned tdthe' fundamental frequencyofresonator H0, rejects the harmonic frequency; Harmonic energy may be coupled back to resonator 81 through concentric lines [2 5 and 9.5,as in Fig. 1. Resonator 8|, being tuned to the harmonic frequency of resonator H0, rejects the fundamental frequency. Phase and amplitude adjusting devices may be used between lines I24, 95 and H6, 96, if desirable. In use of the device as an amplifier, the connecting line between concentric lines I24 and 95 is omitted, the energy to be amplified being introduced through concentric line 95 and removed through line 124.

It is evident to one skilled in the art that energy of both fundamenta1 and harmonic frequencies may be removed as shown in the aforementioned Patent No. 2,425,738 from resonator Hi). It is also evident that resonators I8 and 8| may be replaced by a single resonator of the same type as resonator l H).

In both Figs. 1 and 2, the focussing coil I00 may be omitted, in which case the cathode 14 and focussing electrode 15 are formed in well-known manner so as to provide a beam of electrons travelling in parallel paths.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A high frequency tube structure comprismg mean for producing an electron stream, means including a plurality of hollow resonators along the path of said stream for effecting recurrent bunching of the electrons of the stream, and a plurality of hollow output resonators disposed in the path of the stream and tuned to differing frequencies for abstracting energy from the stream.

2. A high frequency tube structure comprising means for producing an electron stream, plural resonator means along the path of said stream for effecting recurrent bunching of the electrons of the stream at fundamental and harmonic frequencies, an additional resonator positioned in the path of said bunched stream for absorbing energy therefrom, said additional resonator having two simultaneous modes of oscillation at frequencies corresponding to the fundamental frequency of said bunched beam and the harmonic thereof, and means coupled to said additional resonator for extracting energy from said additional resonator at said fundamental and harmonic frequencies.

3. High frequency tube structure comprising means for producing an electron stream, a first .cavity resonator tuned to a predetermined frequency and positioned along the path of said stream in energy-exchanging relation thereto, a second cavity resonator positioned along said path in energy-exchanging relation to said stream and tuned substantially to a harmonic of said predetermined frequency, a third cavity resonator positioned along said path in energy-exchanging relation to said stream and also tuned substantially to said harmonic frequency, and means coupling said second and third resonators together.

4. High frequency tube structure comprising means for producing an electron stream, a first cavity resonator tuned to a predetermined frequency and positioned along the path of said stream in energy-exchanging relation thereto, a second cavity resonator tuned substantially to a harmonic of said predetermined frequency and positioned along said path in energy-exchanging relation to saidstream, a third cavity resonator tuned substantially to said predetermined frequency and positioned along said path in energyexchanging relation'to said stream, and means coupling said first and third resonators together.

5. High frequency tube structure as in claim 3, further including a fourth cavity resonator tuned substantially to said predetermined frequency and positioned along said path in energy-exchanging relation to said stream, and means defining a field-free drift space between said second and third resonators, whereby said first and second resonators serve to velocity modulate the electrons of said stream in non-sinusoidal fashion, and said third and fourth resonators serve to extract high frequency energy from said stream at different harmonically related frequencies.

6. High frequency apparatus comprising means for producing an electron stream, means along the path of said stream for velocity modulating said stream at a fundamental frequency and at a harmonic thereof, means along said stream path for extracting energy of said harmonic frequency from said stream, and means coupling said extracting means to said modulating means.

7. High frequency apparatus comprising means for producing an electron stream, means along the path of said stream for velocity modulating said stream at a fundamental frequency and at a harmonic thereof, means along said stream path for extracting energy of said fundamental frequency from said stream, and means coupling said extracting means to said modulating means.

8. High frequency tube structure comprising a source of electrons, three electron-permeable electrodes aligned with said source and located close to one another to provide two gaps adapted to be successively traversed by the electrons from said source, a first tuned circuit coupled between the center one of said electrodes and one outermost electrode, a second tuned circuit coupled between said center electrode and the other outer electrode, one of said circuits being tuned to a fundamental frequency and the other to a frequency which is substantially a harmonic of said fundamental frequency, and a drift-space-defining member surrounding the path of said electrons on the side of said electrodes opposite from said electron source.

9. Tube structure as in claim 8 wherein said resonant circuits are provided by cavity resonators.

10. Tube structure as in claim 9 wherein means are provided for exciting said two resonators at said fundamental and harmonic frequencies.

11. Tube structure as in claim 8 further comprising output circuit means along the path of said electrons adjacent the other end of said drift-space-defining member.

12. Tube structure as in claim 11 wherein said output means are adapted to abstract both fundamental and harmonic frequencies from said electron stream.

13. Tube structure as in claim 12 wherein said output means are provided by cavity resonator means.

WILLIAM W. HANSEN.

(References on following page) Number;

Name zu bate Hahn Feb 13,1940 Fraenckel Nov.126,-,1940 Hahn H Nov. 26, 1940 Hansen et a1 May 5;;1942 Litton h Dec. 22; 1942 Fisk Mar. 27, 1942 Anderson Oct. 22, 1946 

